Field of the Invention
The present invention relates to an evaluation apparatus for detecting the positions of tips of probes and a probe position inspection method.
Background Art
A semiconductor wafer or a chip obtained by singulating a semiconductor wafer is an object to be measured for which electrical characteristics are evaluated before shipping. When electrical characteristics of an object to be measured are evaluated, a lower surface of an object to be measured is fixed to a surface of a chuck stage by vacuum suction or the like, and then a probe for electrical input and output is brought into contact with an electrode provided in a portion of an upper surface of the object to be measured. In the evaluation of a semiconductor device having a vertical structure through which a large current is vertically passed, the surface of the chuck stage serves as an electrode. In evaluation in which a large current is passed or in which a high voltage is applied, the number of probes is increased.
When electrical characteristics of a semiconductor device are evaluated, it is important to bring a plurality of probes into contact with a surface electrode of the semiconductor device with high positional accuracy. If contact positions between probes and the surface electrode are misaligned, a desired current or voltage may not be applied to the semiconductor device. Moreover, if the probes come in contact with a portion of the semiconductor device other than the surface electrode, the semiconductor device may be damaged. In particular, in the case where a double-sided prober which brings probes into contact with both sides of the semiconductor device is used, the above-described misalignment may cause damage to the semiconductor device.
To reduce contact position misalignment between probes and a semiconductor device, it is desirable to use short probes. However, the lengths of probes tend to be increased so that discharge phenomena may be reduced by increasing the distance between a body portion of a probe card and the semiconductor device. Accordingly, contact position misalignment between probes and a semiconductor device is liable to occur.
It has been known that a non-contact probe position measurement method is used to inspect whether probes constitute a misalignment factor or not. For example, probe positions are measured by image processing using a camera installed to face the probes. In this case, when the positions of tip portions of the probes are measured, a change in the background, variations in the distances between the probes and the camera, variations in focusing accuracy among the probes, the influence of substances attached to the probes, and the like all become disturbance factors and interfere with accurate measurement.
Japanese Patent Application Publication Nos. 2001-189353, 2009-198407, and H05-157790 also disclose probe position evaluation methods. Japanese Patent Application Publication No. 2001-189353 discloses observing the positions and sizes of probe marks obtained by bringing probes into contact with a deformable body. Japanese Patent Application Publication No. 2009-198407 includes a disclosure of the erasing of needle mark on a needle mark transfer member. Japanese Patent Application Publication No. H05-157790 discloses performing an inspection with a measuring needle pressed against a flat transparent glass plate.
The probe inspection in Japanese Patent Application Publication No. 2001-189353 requires a process for recycling the deformable body every time a probe inspection is performed, and requires observation after the transfer of probe marks, thus requiring a long inspection time. Moreover, an evaluation apparatus disclosed in Japanese Patent Application Publication No. 2001-189353 cannot be easily added to a prior-art evaluation apparatus. The needle mark transfer member in Japanese Patent Application Publication No. 2009-198407 also requires a recycling process and observation after the transfer of probe marks, thus requiring a long inspection time. An evaluation apparatus of Japanese Patent Application Publication No. H05-157790 has a complicated structure, and therefore cannot be adapted to a double-sided prober which brings probes into contact with both side of a semiconductor device.